TCP Blocking: How to Fix It

TCP Blocking

Recently, TCP traffic transmission has often been blocked~~ So annoying, so annoying

 

How TCP Blocking Manifests

• • Ping works (the ICMP protocol is functioning normally)

 

• • SSH connections do not work properly, and changing the port does not help

 

• • Unable to use SS/SSR V2 wireguard software normally

 

Problem Details

Because the GFW has
traffic analysis software, and the way it operates is by classifying white-listed IP categories.

Category 1: After analyzing encrypted overseas transmission traffic for a period of time, it collects data on that IP and imposes restrictions on it. The common method now is TCP traffic blocking.

Category 2: In this case, the IPs in a certain IP range have been added to a blacklist. Whenever the GFW is activated, the VPS on that IP is affected as well, causing the issue that even SSH becomes inaccessible.

 

Solutions

1: If your issue is the first category, you can try changing your local IP to solve it (because your local IP has continuously been sending overseas data, the GFW determines that the traffic from your local IP is abnormal)

   
 Solution 1: Reconnect your router to obtain a new IP, or use mobile data to connect to the overseas server IP (change your local machine’s IP)

                             Solution 2: Set up KCPTUN to forcibly convert TCP
traffic into UDP traffic

2: If your issue is the second category and even SSH cannot be used, it means that the IP has already been forcibly added to the blacklist. In this case, you need to change the server IP.

One-click KCPTUN server installation

Applicable to CENTOS, DEBIAN, UBUNTU, and other Linux systems

wget --no-check-certificate https://github.com/kuoruan/shell-scripts/raw/master/kcptun/kcptun.sh
chmod +x ./kcptun.sh
./kcptun.sh

Because KCPTUN requires both a local client on your computer and a server-side component, the download link is below